As recent development of multi-functionality of various kinds of electronic equipment, a multi-directional input device has been more frequently used for the input operation part disposed to operate the equipment. For such a multi-directional input device, rotating or pushing one control knob allows the corresponding input operation, and further tilting the one control knob allows the input operation in the direction in which the control knob is tilted.
Now, a description is provided of an example of a conventional multi-directional input device, with reference to the accompanying drawings. FIG. 24 is a sectional view of a conventional multi-directional input device. FIG. 25 is an exploded perspective view thereof. FIG. 26 is a top view thereof. With reference to these drawings, rotational encoder 1 including a push-on switch incorporates an incremental encoder element and a switch element in the space formed by a case member and a cover member thereof. When operating shaft 2 projecting upwardly from the center position of the cover member is rotated, two-phase pulse signals having a phase difference are supplied from the encoder element through terminals. When operating shaft 2 is pressed, the switch element is operated and electrical continuity is established between predetermined ones of the terminals.
Rotational encoder 1 is mounted on upper substrate 5 shaped into a regular octagon as seen from the top. Upper substrate 5 is supported by a pair of first support shafts 9 so as to be rockable about first rocking axis line M-M of frame 7 surrounding the upper substrate. Frame 7 is supported with respect to rocking supports 11A provided on lower substrate 11 by a pair of second support shafts 13 so as to be rockable about second rocking axis line N-N. First rocking axis line M-M is orthogonal to second rocking axis line N-N. On lower substrate 11, press switches 15A, 15B, 15C, and 15D are disposed equidistantly from operating shaft 2 in the center at a pitch of 90°. Pressing projections 5A, 5B, 5C, and 5D projecting from the bottom face of upper substrate 5 are faced to the operating buttons of the corresponding switches. In the positions between pressing projections 5A, 5B, 5C, and 5D on the bottom face of upper substrate 5, control projections 5E, 5F, 5G, and 5H projecting downwardly are also provided.
The conventional multi-directional input device is structured as above. When the device is used, one control knob 17 is attached to operating shaft 2 of rotational encoder 1 to provide a mounting state.
Next, a description is provided of the operation in the mounting state. Rotating control knob 17 rotates operating shaft 2 of rotational encoder 1 and operates the encoder element, thereby providing incremental encoder output. Pressing control knob 17 in the perpendicularly downward direction moves operating shaft 2 downwardly via control knob 17 and operates the switch element. Tilting control knob 17 in the respective directions in which press switches 15A through 15D are disposed rocks upper substrate 5 in the corresponding directions. For example, as shown by the arrow in FIG. 24, control knob 17 is tilted in the direction in which press switch 15A is disposed. Then, upper substrate 5 rocks so that the side of pressing projection 5A lowers. Lowered pressing projection 5A presses the operating button of press switch 15A, thus switching the state of press switch 15A. At this time, control projections 5E and 5H adjacent to pressing projection 5A are brought into contact with lower substrate 11, thus stopping the tilting of upper substrate 5. Next, removing the tilting force allows press switch 15A to self-restore to the original state thereof. The restoring force pushes pressing projection 15A back to the inoperative state of FIG. 24 in which upper substrate 5 is positioned in a horizontal state. For example, Patent Document 1 is known as the information on related art of the present invention.
In order to allow the rocking operation of upper substrate 5 in the tilting operation of control knob 17, the conventional multi-directional input device has the following structure. Upper substrate 5 is supported with respect to frame 7 by the pair of first support shafts 9 so as to be rockable, and frame 7 is supported with respect to lower substrate 11 by the pair of second support shafts 13 so as to be rockable. Further, rotational encoder 1 is mounted on upper substrate 5. With this structure, the stress in the perpendicularly downward direction applied when control knob 17 is pressed is concentrated on the above small supporting portions. For this reason, an extended period of repeated pressing operations in the perpendicularly downward direction or repeated tilting operations can cause scraping or abrasion in the portions supporting the shafts, thus increasing the play and rattle in the above portions.
[Patent Document 1] Japanese Patent Unexamined Publication No. 2004-087290